London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

Large stretches of London’s main orbital road should be put into tunnels in a £30 billion scheme to improve the quality of life, according to a report commissioned by the Mayor.

Cars, lorries and motorbikes would be sent underground on the North and South Circular to replace the congested routes with miles of space at street-level for residents, cyclists and pedestrians.

The bold proposal is greater in ambition than the current £15 billion Crossrail project under the capital and is the most eye-catching plan from the influential Roads Taskforce.

It is the first strategic review for decades of London’s roads which Boris Johnson believes have been overlooked even though they account for 80 per cent of passenger trips.

Sources stress the tunnelling is not designed to make way for more cars but to improve the space at ground level for pedestrians, cyclists and parks while improving the environment by cutting vehicle emissions.

They insist a radical solution is needed. Central London has lost 30 per cent of its capacity for motor vehicles in a decade to schemes such as cycle lanes and pedestrianisation of areas like Exhibition Road.

The task is made urgent because London’s population is forecast to grow by 1.25 million by 2031, adding 14 per cent to road congestion.

A “flyunder” is proposed at Brent Cross shopping centre beneath the six-lane North Circular. A park could be created on top.

But the boldest plan is for the South Circular which the Mayor’s experts want to send underground to give the the Mayor’s experts want to send underground to give the area to a more residential feel.

A further tunnel could be built to replace the Hammersmith flyover with a “flyunder” between Hogarth roundabout and Earl’s Court.

Public spending on the projects could be subsidised by “value capture” — a levy on new properties whose values would soar due to the improved environment.

“It’s not about diverting traffic from the M25 to create additional car capacity, it is about freeing up space on the surface to improve air quality, the quality of life and space for walking and cycling,” said a transport source.

Authors of the reports have been impressed by tunnelling schemes in Stockholm and Oslo to divert traffic underground and create greener cities.

Among the innovations to maximise use of road space, the report proposes “dynamic lane-management” which would switch use of a roads between bus lanes at peak, loading zones between peaks and residents’ parking at the end of the day.

Mobile phone technology can be used to monitor the flow of pedestrians at a crossing and phase the lights green for people to cross at busy times. It is a variation of the SCOOT system that was used effectively during the Olympics to prioritise official vehicles.

The Roads Taskforce report proposes a London-wide 20mph speed limit which would benefit in particular benefit outer boroughs and help to calm high streets and make them more populous. Because capital spending in last month’s government spending review was protected, plans for major improvements to outer London bottlenecks including Five Ways in Croydon remain on track.

Authors of the report want to promote inner London areas such as King’s Cross and Vauxhall as places to live despite them being transport interchanges set to gain tens of thousands more homes.

The Roads Taskforce report has been a more than a year in the making with contributions from London boroughs, cycle groups and motorising organisations such as the RAC.

In the next stage, the Mayor will ask Transport for London to produce a feasibility study on individual projects.